Mapping crown rust resistance in the oat diploid accession PI 258731 (Avena strigosa)

Authors: CHOWDHURY, RAWNAQ - Oak Ridge Institute For Science And Education (ORISE); Gordon, Tyler; BABAR, ALI - University Of Florida; HARRISON, STEPHEN - Louisiana State University Agcenter; Kianian, Shahryar; Esvelt Klos, Kathy

Submitted to: PLOS ONE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/13/2023
Publication Date: 2/2/2024
Citation: Chowdhury, R.N., Gordon, T.C., Babar, A., Harrison, S.A., Kianian, S., Esvelt Klos, K.L. 2024. Mapping crown rust resistance in the oat diploid accession PI 258731 (Avena strigosa). PLOS ONE. 19(2). https://doi.org/10.1371/journal.pone.0295006.
DOI: https://doi.org/10.1371/journal.pone.0295006

Interpretive Summary: PI 258731 is a wild oat (A. strigosa) accession originally received by the National Plant Germplasm System in 1959 from Galicia, Spain and has been shown to be moderately resistant or resistant to crown rust disease. Crown rust disease commonly causes grain yield losses in cultivated oat of 20%. Resistance from this accession has been successfully transferred into cultivated oat. We mapped the location of the gene responsible for crown rust resistance in the original species. Two pathogenic races of crown rust were used to screen the population under growth chamber conditions. Collected data demonstrated the presence of a single resistance gene for crown rust disease. This study determined that the identified gene was completely responsible for crown rust resistance observed in the field. Comparison of the location of this resistance gene in the wild oat map with the location where the gene inserted into cultivated oat (A. sativa) suggested that genetic markers may be useful as tools for markers assisted oat breeding.

Technical Abstract: Oat crown rust, caused by Puccinia coronata Corda f. sp. avenae Eriks. (Pca), is a major biotic impediment to global oat production. Crown rust resistance has been described in oat diploid species A. strigosa accession PI 258731 and resistance from this accession has been successfully introgressed into hexaploid A. sativa germplasm. The current study focuses on 1) mapping the location of QTL containing resistance and evaluating the number of quantitative trait loci (QTL) conditioning resistance in PI 258731; 2) understanding the relationship between the original genomic location in A. strigosa and the location of the introgression in the A. sativa genome; 3) identifying molecular markers tightly linked with PI 258731 resistance loci that could be used for marker assisted selection and detection of this resistance in diverse A. strigosa accessions. To achieve this, A. strigosa accessions, PI 258731 and PI 573582 were crossed to produce 157 F5:6 recombinant inbred lines (RILs) through single seed descent. Parents and RILs were genotyped with the 6K Illumina SNP array which generated 168 segregating SNPs. Seedling reactions to two isolates of Pca (races TTTG, QTRG) were consistent with a single gene segregating in this population. Linkage mapping placed the PcPI 258731 resistance in 8 cM region on LG7. QTL analysis of field reaction data was consistent with the seedling data and the results of interval mapping (MIM) revealed a major QTL (QPc.FD-AS-AA4) for field resistance. SNP marker assays were developed and tested in 125 diverse A. strigosa accessions that were rated for crown rust resistance in Baton Rouge, LA and Gainesville, FL and as seedlings against races TTTG and QTRG. Our data proposed SNP marker GMI_ES17_c6425_188 as a candidate for use in marker-assisted selection, in addition to the marker (GMI_ES02_c37788_255) suggested by Rine’s group, which provides an additional tool in facilitating the utilization of this gene in oat breeding programs.